Lifting apparatus

ABSTRACT

A lifting spreader bar suitable for lifting pipe or other articles from one floating vessel to another wherein such vessels could have movement relative to each other, said spreader bar having an elongate structure, lifting lines extending from opposite ends of said elongate structure, means for establishing a preselected tension in said lifting lines while they are moving relative to said elongate structure, means indicating such relative movement of the lifting lines, a hoisting connection to the central portion of said elongate structure, and means for indicating the angle of said hoisting connection with respect to vertical.

United States Patent Foster Sept. 24, 1974 LIFTING APPARATUS 3,534,355 10/1970 Fathauer 212/39 x 1 1 hwemon Robert Don Foster, 332321322 313?? fiiil'iff?.".'.f:jjjjj 554131 23 [73] Assignee: CRC-Crose International, Inc.,

Houston, Tex. Primary ExaminerRichard A. Schacher Assistant Examiner-Bruce H. Stoner, Jr. [22] Flled: July 1971 Attorney, Agent, or Firm-Jack R. Springgate; Joe E. 21 App]. No.: 167,386 Edwards; y

[57] ABSTRACT a" 294/81 A lifting spreader bar suitable for lifting pipe or other [58] Fie'ld R 81 SF articles from one floatmg vessel to another wherem 294/86 R R 88 f such vessels could have movement relative to each 2547189, 73/496 other, sald spreader bar havmg an elongate structure,

lifting lines extending from opposite ends of said elon- [56] References Cited gate structure, means for establishing a preselected tension in said lifting lines while they are moving rela- UNITED STATES PATENTS tive to said elongate structure, means indicating such 1,677,695 7/1928 Vogt 294/81 R relative movement of the lifting lines, a hoisting con- 2,l76,979 Platz nection to the central portion of aid elongate true- 3 34 ture, and means for indicating the angle of said hoist- 3:314:657 4/1967 p ri ti tifrliile i ii. $1.. 252 189 ing connection with respect to vertical 3,318,545 5/1967 Tobey 242/184 4 Claims, 2 Drawing Figures PATENTED 2 74 ROBERT D. FOSTE INVENTQR.

1 LIFTIING APPARATUS BACKGROUND OF THE INVENTION In the laying of pipelines underwater such as from offshore wells to shore, considerable difficulty is encountered in supplying the lay barge with pipe when the wind and sea Conditions are such that there is a substantial relative movement between the lay barge and the pipe supply barge. Many times the laying of the underwater pipeline has been stopped for several days because of being unable to transfer pipe from the supply barge to the lay barge.

Also on other offshore operations in which heavy materials or supplies are transferred between two relatively moving vessels, the amplitude of such movement, usually caused by the waves, can result in an inability to safely transfer such materials and supplies.

SUMMARY The present invention relates to an improved lifting spreader bar allowing pipe to be transferred between floating vessels even in relatively high seas.

An object of the present invention is to provide an improved lifting apparatus which compensates for relative movement between vessels to allow articles to be transferred even in relatively high seas.

Another object is to provide an improved pipe lifting apparatus in which the danger inherent in sideward movement of the pipe as it is lifted is eliminated.

A further object is to provide an improved pipe lifting spreader bar with which heavy pipe sections can be lifted and transferred between floating structures without shock loading of the lifting equipment and in which the potential damage to vessels, lifting equipment and pipe is eliminated.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and advantages of the present invention are hereinafter set forth and explained with reference to the drawings wherein:

FIG. 1 is an elevation view of a lay barge and a supply barge with the improved lifting spreader bar of the present invention being shown lifting a pipe section on the supply barge preparatory to transferring the pipe to the lay barge.

FIG. 2 is an enlarged detail elevation view of the improved spreader bar of the present invention lifting a section of pipe.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1, the lay barge is shown with a portion of the pipeline being laid extending from one end and a crane 12 on the other end. A pipe supply barge 14 is shown moored close to the lay barge 10 so that the supply of pipe can be lifted from the supply barge 14 to the lay barge 10. By using the improved spreader bar 16 of the present invention, such lifting and transfer of pipe can be done safely even with substantial relative movement between the barges 10 and 14. The hoisting line 18 from crane 12 is connected to the central portion of spreader bar 16 as hereinafter explained.

The spreader bar 16 includes an elongate structure 20 composed of a plurality of members suitably secured together, as by welding, the hoisting connection 22 to which the line 18 is connected and the two spreader bar lines 24 extending from the sheaves 23 at opposite endsof structure 20. Suitable pipe engaging clamps 26 are attached on the ends oflines 24 connections 28 are provided so may be easily and conveniently connected to the pipe ends as shown in FIG. 2. Tensioning means 30, hereinafter described, is provided on spreader bar 16 to establish a tension in the lines 24 after the clamps 26 have been connected to'the pipe ends. Such tensioning means 30 is controlled from the crane 12.

Previously, the crane operator was not able to determine the exact relative movement of the two barges It) and 14 or the verticality of the hoisting line 18 when a pipe is ready to be lifted from barge 14. To provide the crane operator with an indication of the relative movement of the two vessels, or more particularly the relative movement of the spreader bar 16 with respect to the pipe P, one of the lines 24 is passed over the sheave 23 which is connected to drive generator 34 responsive to the movement of the line 24. Generator 34 may be a small D.C. generator or any other suitable device for transmitting an indication of the relative movement of the spreader bar with respect to the pipe. Generator 3 4 is electrically connected to an indicator (not shown) in crane 12 which indicates both the direction and rate of movement of the spreader bar 16 relative to the pipe P.

Also to assist the crane operator, the spreader bar hoisting connection 22 includes a plumb angle sensor 36 which transmits to the crane 12'an indication of the relative verticality of hoisting line 18. Such plumb angle sensor is preferably mounted as a part of the hoisting line 18 rather than as a part of the spreader bar 16. Plumb angle sensor 36 may be a pair of potentiometric pendulum as sold by Humphrey, Inc. under the model designations CF41, (IP43, CP47 and .CP48. Such sensors have an output indicating the slope and direction of hoisting line 18 with respect to vertical. The sensors are mounted at right angles to each other to provide the indication of slope in all directions.

With the indication from the plumb angle sensor 36, the crane operator can avoid lifting pipe when his hoisting line is not vertical and, thus, avoid the danger and damage which would be caused by the induced horizontal movement of the pipe responsive to the angularity of the hoisting line from vertical as it is first lifted.

The relative motion indication provided by the generator 34 allows the operator of the crane 12 to lift the pipe P off its support on barge 14 at times when the relative movement of the two vessels is the most desirable for lifting. For example, as the pipe P approaches its nearest position (uppermost) to spreader bar 16, lifting can be accomplished without any shock loading and without danger of the barge l4 rising to hit the pipe after it is supported from spreader bar 16 The tensioning means 30 as previously explained is connected to the spreader bar lines 24 to exert a preselected tension on such lines after they are connected to the pipe. Such preselected tension is a tension which maintains the lines 24 tight, i.e., does not allow any slackness, but does not exert sufficient force to lift the pipe P.

Such tensioning means 30 includes the block and tackle 38 to which the lines 24 are connected and the actuator 40 which is connected to one of the pulleys of block and tackle 38 and to the structure to vary the distance between the two pulleys of block and tackle 38. As can be seen, when actuator 40 is subjected to a preselected pressure from hydraulic tank 42, actuator 40 tends to retract its arm 44 to shorten the length of lines 24 extending from spreader bar 16 and thus create a tension in lines 24 proportional to the preselected pressure. The desired tensioning maintains a relatively uniform load on the lines 24 as they move in and out on demand. Such tensioning may be achieved by any suitable tensioning means, one example being herein described.

The solenoid valve 46 in the hydraulic line from tank 42 to actuator 40 is normally shut during lifting to effectively prevent movement of actuator 40 and thus inactivate tensioning means 30. To activate tensioning means 30, valve 46 which is controlled from crane 12 or by someone on barge 14 is opened. With valve 46 open, the preselected hydraulic pressure is supplied to actuator 40 responsive to the gas pressure (preferably nitrogen) delivered from the gas bottle 48 under control of valve 50 to tank 42 above the level of hydraulic fluid therein. With tensioning means 30 actuated, the preselected tension in lines 24 is maintained until solenoid valve 46 is closed as hoisting line 18 is raised.

In order to connect lines 24 to the pipe P, the pressure on actuator 40 is vented by closing valve 50, and opening solenoid valve 46 and vent valve 52 on tank 42. ln this condition all pressure is vented from actuator 40 and lines 24 can be manually extended to their full length for connection to pipe P with spreader bar 16 a safe distance thereabove.

Another way of making the lines 24 ready to connect to a pipe is to open valve 46 after the pipe is resting on the barge 10. With valve 46 open, the lines 24 are extended by lifting the spreader bar 20. The valve 46 is closed and the spreader bar 20 is lowered to allow clamps 26 to be removed. The spreader bar 20 is then moved to the barge l4 and the clamps 26 are secured to the ends of a pipe P with the lines 24 slack. Opening the valve 46 applies the desired tensioning of lines 24.

From the foregoing it canbe seen that the present invention provides an improved apparatus for lifting and transferring articles such as pipe from one location to another location wherein there is relative movement between such locations. This improved apparatus allows such lifting to be accomplished safely and without shock loading. Such apparatus thus avoids the damage to the apparatus, to the location and to the article being lifted.

What is claimed is:

1. A spreader bar comprising an elongate structure,

a central hoisting connection on said structure,

a lifting line extending from each end of said structure,

means for establishing a pre-selected tension on both of said lifting lines including,

a block and tackle connected to said lifting lines to control the length of each line extending from said structure,

a piston and cylinder connected to said block and tackle to establish a preselected tension in said lifting lines,

a hydraulic reservoir connected to deliver hydraulic fluid to said cylinder, and

a gas reservoir connected to deliver gas under pressure to said hydraulic reservoir to urge said hydraulic fluid to exert a pressure in said cylinder on said piston.

2.'A spreader bar according to claim 1 including a control means having ing a hoisting line,

an elongate spreader bar,

means located centrally of said spreader bar for connecting said hoisting line thereto,

a lifting line extending from each end of said spreader bar, and

means for applying a preselected tension to said lifting lines,

said lifting lines being extendible and retractible responsive to the applied tension and the load connected to said lines,

said tension applying means including,

a block and tackle connection to said lifting lines to control the length of each line extending from said structure,

a piston and cylinder connected to said block and tackle connection to apply the preselected tension in said lifting lines when they are connected to an article to be lifted,

a hydraulic reservoir connected to deliver hydraulic fluid to said cylinder, and

a gas reservoir connected to deliver gas under pressure to said hydraulic reservoir to urge said hydraulic fluid to exert a pressure in said cylinder on said piston.

4. An apparatus for lifting, comprising a hoisting line,

a lifting line,

means connecting between said hoisting line and said lifting line,

said connecting means including means for controlling the length of said lifting line,

a pressure responsive actuator connected to said length controlling means to exert a tension on said lifting line,

a source of fluid under pressure,

control means for delivering said fluid to said pressure responsive actuator to tension said lifting line,

a remotely controlled valve adapted to close communication between said source and said actuator, and

at least that portion of the fluid delivered to said actuator is a hydraulic fluid whereby when said remotely controlled valve is shut said actuator is locked in position and said lifting line is held against movement to allow lifting of said hoisting line.

Patent 5, 37, 98 Dated September 2I,l97+

Inventor(s) Robert Don Foster It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 2, lines 5 and LI,

"clamps 26 are attached on the ends of lines 2A connections 28 are provided so may be easily and conveniently" should read:

"clamps 26 are attached on the ends of lines 24 and swivel connections 28 are provided so that the clamps 26 may be easily and conveniently" Signed and sealed this 18th day of March 1.975.

(SEAL) Attest:

C. Z IARSHALL DANN RUTZ C. PIASON Commissioner of Patents Attesting Officer and Trademarks ORM PO-\O$0 (10-69) U 5COMM--DC 60376.P69 u.s, GOVERNMENT rmu'nus orncz; 930 

1. A spreader bar comprising an elongate structure, a central hoisting connection on said structure, a lifting line extending from each end of said structure, means for establishing a pre-selected tension on both of said lifting lines including, a block and tackle connected to said lifting lines to control the length of each line extending from said structure, a piston and cylinder connected to said block and tackle to establish a preselected tension in said lifting lines, a hydraulic reservoir connected to deliver hydraulic fluid to said cylinder, and a gas reservoir connected to deliver gas under pressure to said hydraulic reservoir to urge said hydraulic fluid to exert a pressure in said cylinder on said piston.
 2. A spreader bar according to claim 1 including a control means having a remotely controlled valve adapted to close communication between said hydraulic reservoir and said cylinder, and the fluid delivered to said cylinder is a hydraulic fluid whereby when said remotely controlled valve is shut said cylinder and piston are locked in position and said lifting lines are held against movement to allow lifting of said spreader bar.
 3. An apparatus for lifting elongate articles, comprising a hoisting line, an elongate spreader bar, means located centrally of said spreader bar for connecting said hoisting line thereto, a lifting line extending from each end of said spreader bar, and means for applying a preselected tension to said lifting lines, said liFting lines being extendible and retractible responsive to the applied tension and the load connected to said lines, said tension applying means including, a block and tackle connection to said lifting lines to control the length of each line extending from said structure, a piston and cylinder connected to said block and tackle connection to apply the preselected tension in said lifting lines when they are connected to an article to be lifted, a hydraulic reservoir connected to deliver hydraulic fluid to said cylinder, and a gas reservoir connected to deliver gas under pressure to said hydraulic reservoir to urge said hydraulic fluid to exert a pressure in said cylinder on said piston.
 4. An apparatus for lifting, comprising a hoisting line, a lifting line, means connecting between said hoisting line and said lifting line, said connecting means including means for controlling the length of said lifting line, a pressure responsive actuator connected to said length controlling means to exert a tension on said lifting line, a source of fluid under pressure, control means for delivering said fluid to said pressure responsive actuator to tension said lifting line, a remotely controlled valve adapted to close communication between said source and said actuator, and at least that portion of the fluid delivered to said actuator is a hydraulic fluid whereby when said remotely controlled valve is shut said actuator is locked in position and said lifting line is held against movement to allow lifting of said hoisting line. 